I use url connection (http).
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
NSString *filePath; /* .../link.plist */
[data writeToFile:filePath atomically:YES];
}
After connection, I check result file (link.plist)
- (void)checkLinkResult {
NSString *filePath; //link.plist
NSString *result = [[NSString alloc] initWithContentsOfFile:filePath];
}
It works fine.
But I want to check Result String, directly, without making file.
"NSData -> file -> NSString" (now) ====> "NSData -> NSString" (i want)
Help me plz.
It's dependent your data.
If your data is Image
UIIMage * image = [[UIImage alloc] initWithData:Receivedata
If data is string
NSMutableString *string = [[NSMutableString alloc] initwithData:Receivedata encoding:nil]
In didReceiveData write to an NSMutableData object, then in checkLinkResult create a string from the NSMUtableData using the appropriate encoding.
It's actually how it's done in the apple NSConnection tutorial.
Follow the following steps:
Declare a file scope NSMutableData instance.
in your connection:DidRecieveData: callback append "data" to the previously created NSMutableData instance.
In connectionDidFinishLoading: callback use initWithData:encoding: of NSString and pass the NSMutableData instance and NSUTF8StringEncoding as parameters.
Related
Im getting a BSON response from the server.I want to save it to a file and read that file instead of directly reading the response.
This is the method where im getting the response
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
// NSString* path = [[NSBundle mainBundle] pathForResource:#"data"
ofType:#"txt"];
// NSString* content = [NSString stringWithContentsOfFile:path
encoding:NSUTF8StringEncoding
error:NULL];
[self readTillEOF];
NSRange range = NSMakeRange(0, [data length] - 3);
NSData *refinedData = [data subdataWithRange:range];
[delegate didRecieveTillEof:refinedData];
}
can anyone please help me with this.
Thanks in advance.
EDIT : Take a look at this how to convert BSON into NSString
Check if u can convert your data into array or dictionary and that can be used for saving in document directory like this.
I'm working with facebook connect and trying to handle the JSON object that i'm receiving.
I invoked the requstWithGraphPath method and need to get back a JSON object,
tried to parse it and getting an error:
SBJSON *parser = [[SBJSON new] autorelease];
NSData *data = [[NSData alloc] initWithData:result];
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; -> in this line - "[__NSCFDictionary length]: unrecognized selector sent to instance"
NSArray *events = [parser objectWithString:jsonString];
What's the problem?
Can I get the string in an other way or parse the object differently?
Thanks.
If you are working with the delegate callback
- (void)request:(FBRequest *)request didLoad:(id)result;
the parsing work has been done for you. Traverse the NSDictionary or NSArray to find the data you are looking for. If you are working with the delegate callback
- (void)request:(FBRequest *)request didLoadRawResponse:(NSData *)data;
you should initialize an NSString with the data, and use the category method that SBJSON adds to NSString for creating an id. That is assuming the data is data that constructs a string.
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
id result = [jsonString JSONValue];
Are you sure the error happens on that line, or does it happen on the line above?
If result is an NSDictionary (or CFDictionary, same thing), then it is already parsed and you do not need to do that yourself — and it could cause that error message too, on the line above.
The line:
data = [[NSData alloc] initWithData:result];
is almost certainly not what you want to do, as it is equivalent to
data = [result copy];
assuming that result is an NSData object (or NSMutableData), which I'm guessing it isn't.
I'm creating an app which downloads a .zip file from S3 server.
All works fine. Now I want to be able to interrupt the current download. If I could save the current size (bytes) of the file, I would be able to send a new request with a range header for the other part of the file.
Problem lies in the fact that I cannot determine the size of the 'already' downloaded content, because I can only see the file in my directory when the download is completed. So if I interrupt, there isn't a partial file saved.
At this time I use the following code for this:
-(void) downloadFile:(NSMutableArray*)paramArray withDict:(NSMutableDictionary*)options
{
NSLog(#"DOWNLOAD THREAD STARTED");
NSString * sourceUrl = [paramArray objectAtIndex:0];
NSString * fileName = [paramArray objectAtIndex:1];
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *newFilePath = [documentsDirectory stringByAppendingString:fileName];
NSError *error=[[[NSError alloc]init] autorelease];
NSURLConnection *fileURL = [NSData dataWithContentsOfURL: [NSURL URLWithString:sourceUrl]];
BOOL response = [fileURL writeToFile:newFilePath options:NSDataWritingFileProtectionNone error:&error];
if (response == TRUE)
{
NSLog(#"DOWNLOAD COMPLETED");
[self performSelectorOnMainThread:#selector(downloadComplete:withDict:) withObject:paramArray waitUntilDone:YES];
}
else
{
NSLog(#"Something went wrong while downloading file.");
NSString *callback = [NSString stringWithFormat:#"downloadInterrupted('%#');",fileName];
[webView stringByEvaluatingJavaScriptFromString:callback];
}
[pool drain];
}
AsiHTTP isn't an option because there are issues with the PhoneGap I'm using.
A better idea is to download the file asynchronously. This has several advantages: The most important one is that your user interface stays responsive. The user can go on using your application while it is downloading and waiting for the data. If the data you are downloading is absolutely essential for the application, display some sort of loading indicator.
You can easily start the asynchronous download via
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:sourceUrl]];
NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];
Now, how do I get the downloades data in an NSData object? You implement the following delegate methods for self:
-connection:didReceiveData:
-connection:didFailWithError:
-connectionDidFinishLoading:
The idea is that you are notified whenever some data drops in through your connection or anything important else happens (success or failure for exmple). So you are going to declare a temporary NSMutableData object as an instance variable (say downloadData) and write to it until the download is complete. Do not forget to initialize the empty object and declare a property as well!
-connection:didReceiveData: is called whenever some sort of data (that is, a part of your downloaded file) arrives. So you are going to append it to your temporary object like this:
-(void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[self.downloadData appendData:data];
}
Once the download has finished (successfully), the next delegate method is called:
-(void) connectionDidFinishLoading:(NSURLConnection *)connection {
//do whatever you need to do with the data in self.downloadData
}
If the downloads fails, -connection:didFailWithError: is called. You can then save the temporary object, get its size and resume the download later. [self.downloadData length]; gets you the size in bytes of the data in your object.
You are going to have to use a lower level api.
time to read up on unix socket programming. http://www.fortunecity.com/skyscraper/arpanet/6/cc.htm would be a good start.
It really won't be too hard. honest.
I recommend you to build a method that save data chunk every 1, 2 MB or maybe less in order to resume properly your download and avoid memory crash.
This because if you get an error in your transfer maybe your file could be result corrupted.
Anyway send a range HTML header is pretty simple
NSFileHandle *fileHandler = [NSFileHandle fileHandleForReadingAtPath:dataPreviouslySavedPath];
[fileHandler seekToEndOfFile];
unsigned long long int range = [fileHandler offsetInFile];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:downloadURL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:20.0];
[request setValue:[NSString stringWithFormat:#"bytes=%lli-", range] forHTTPHeaderField:#"Range"];
NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
Hope this help you.
using iphone sdk 4.0. The callback for an http request gives data as an NSData object
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
// Append the data received to our data
[theData appendData:data];
}
In my php script on the server i am returning an array as follows
var_dump($array).
How do i get my array back from the NSMutableData object 'theData' obove on my iphone.
Thanks
You have a string describing your array (or maybe several arrays?) stored as a sequence of bytes in your NSMutableData object. In order to turn it back into an array you're going to need to parse the var_dump output, which is likely to be arduous.
If you can find a library (or roll your own code) to return your data in Apple plist format, your task will be much easier: you can use
[NSPropertyListSerialization propertyListFromData:mutabilityOption:format:errorDescription:]
which takes an NSData (or NSMutableData) pointer as its first argument. Try http://code.google.com/p/cfpropertylist/ for a starting point.
From the example code at the cfpropertylist page:
$plist = new CFPropertyList();
$td = new CFTypeDetector();
$guessedStructure = $td->toCFType( $array );
$plist->add( $guessedStructure );
// and then return the plist content with
$plist->toXML()
and in your iOS code:
NSString *errorString = nil;
NSArray *array = [[NSPropertyListSerialization
propertyListFromData:theData
mutabilityOption:NSPropertyListImmutable
format:nil
errorDescription:&errorString] retain];
I would likely use YAJL on iOS, and $var = json_encode($array); in the PHP. Then in the iOS, I would parse that content from the NSData input like:
YAJLParser *parser = [[YAJLParser alloc] initWithParserOptions:YAJLParserOptionsAllowComments | YAJLParserOptionsCheckUTF8];
parser.delegate = [[[MyArrayParserDelegate alloc] init] autorelease];
[parser parse:data];
NSArray *thePhpArrayReceived = parser.delegate.resultantArray;
Please check out how to structure the delegate, and get YAJL here : Get YAJL + Readme
PHP outputs text so you will have to read that NSData as NSString and then parse out the array data according to the format specified by var_dump. As a starting point, the following code snippet should print out the array (as text) to your console:
NSString * dump = [[NSString alloc] initWithData:theData
encoding:NSUTF8StringEncoding];
NSLog(#"%#", dump);
[dump release];
As Seamus Campbell points out, there are better ways of doing this. Another option would be to output XML from your PHP script, and then use Cocoa's XML parsing methods to retreive the array.
I'm getting an image over HTTP, using NSURLConnection, as follows -
NSMutableData *receivedData;
- (void)getImage {
self.receivedData = [[NSMutableData alloc] init];
NSURLConnection *theConnection = // create connection
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
[receivedData appendData:data];
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection {
[connection release];
UIImage *theImage = [UIImage imageWithData:receivedData];
}
Usually it works just fine, but sometimes I'm seeing this get logged - : Corrupt JPEG data: premature end of data segment
At this point, the image does not completely render. I'll see maybe 75% of it, and then the lower right hand corner is a grey box.
Any ideas on how to approach fixing this? Am I constructing my image improperly?
Your HTTP code looks correct. You might want to log the size of the receivedData once it's done loading and compare it to the expected size of the image on the server. If it's the expected size, then maybe the image itself is corrupted on the server.
ASI-HTTP can fix this problem.
NSURL *coverRequestUrl = [NSURL URLWithString:imageStringURL];
ASIHTTPRequest *coverRequest = [[ASIHTTPRequest alloc] initWithURL:coverRequestUrl];
[coverRequest setDelegate:self];
[coverRequest setDidFinishSelector:#selector(imageRecieved:)];
[appDelegate.queue addOperation:coverRequest];
[appDelegate.queue go];
My queue variable in appDelegate is ASINetwork queue object. Because I send asynchronous request, so I use it.
- (void)imageRecieved:(ASIHTTPRequest *)response
{
UIImage *myImage = [UIImage imageWithData:[response responseData]];
}
I fixed this problem by using an NSMutableDictionary.
NSMutableDictionary *dataDictionary;
In my loadData function, I define my data:
NSMutableData *receivedData = receivedData = [[NSMutableData alloc] init];
Then I load the data into my dictionary where the key is [theConnection description] and the object is my data.
[dataDictionary setObject:receivedData forKey:[theConnection description]];
That way in the delegates, I can look up the correct data object for the connection that is passed to the delegate and save to the right data instance otherwise I end up with the JPEG munging/corruption problem.
In didReceiveData, I put:
//get the object for the connection that has been passed to connectionDidRecieveData and that object will be the data variable for that instance of the connection.
NSMutableData *theReceivedData = [dataDictionary objectForKey:[connection description]];
//then act on that data
[theReceivedData appendData:data];
Similarly, in didReceiveResponse, I put:
NSMutableData *theReceivedData = [dataDictionary objectForKey:[connection description]];
[theReceivedData setLength:0];
And in connectionDidFinishLoading:
NSMutableData *theReceivedData = [dataDictionary objectForKey:[connection description]];
img = [[UIImage alloc] initWithData:theReceivedData];
And this seems to work very well. By the way, my code is based on Apple's tutorial for NSUrlConnection with the addition of an NSMutableDictionary to keep track of individual connections. I hope this helps. Let me know if you want me to post my full image handling code.
I have seen this also. If you save the data to a file and then read the data back into an image, it works perfectly. I suspect there is http header information in the jpeg image data.
Hope someone finds a solution to this because the save to file workaround sucks.
// problem
UIImage *newImage = [UIImage imageWithData:receivedData];
// crappy workaround
[receivedData writeToFile:[NSString stringWithFormat:#"a.jpg"] atomically:NO];
UIImage *newImage = [UIImage imageWithContentsOfFile:#"a.jpg"];
Copying the NSData content using receivedData = [NSData dataWithBytes:receivedData.bytes length:receivedData.length] may be helpful too (and it's more efficient than saving to and reading from the disk).
A possible reason for this is that the original receivedData object does not retain its content (e.g. when created using [NSData dataWithBytesNoCopy:length:]) and you try to read them after they are freed.
This is likely when you encounter this problem on another thread from the thread that created the NSData object.